1. Field of the Invention
The invention relates to a process for making zeolites. More particularly it relates to making ZSM-5 or ZSM-11 zeolites which, in their synthesized form, are low in nitrogen content.
2. Summary of the Prior Art
Zeolites of the ZSM-5 type (e.g. ZSM-5 and ZSM-11) and others like zeolite Beta, TEA mordenite and ZSM-12 have been crystallized from a solution containing organic cations, particularly including alkyl ammonium cations. Zeolites ZSM-5 and ZSM-11, in general, have a pore size greater than the 5 Angstrom materials and less than the large pore zeolites such as Zeolite X, Zeolite Beta and the like.
U.S. Pat. No. 3,702,886 is concerned with the zeolite ZSM-5 and some of its uses. U.S. Pat. No. 3,709,979 discloses and claims ZSM-11. So the description of these two zeolites may be complete, the two U.S. patents are hereby incorporated herein by reference. Neither of these patents suggests or teaches the use of ZSM-5 or ZSM-11 seeds to prepare the respective zeolites.
In addition, U.S. Pat. No. 3,119,659 discloses the use of the same type of molecular sieve being produced, as do U.S. Pat. Nos. 3,321,272 and 3,532,459. U.S. Pat. No. 3,671,191 teaches a general seeding technique, as does an article by Zhdanov, "Molecular Sieve Zeolites-I" ACS, 1971, pages 36 and 37. German Pat. No. 2,212,810 discloses the use of a mixture of ethyl alcohol, ammonium hydroxide and triethylamine to make ZSM-8 and of a mixture of ammonia, propyl alcohol and tripropylamine to make ZSM-5.